The present invention relates to devices and methods for detection and diagnostic localization of plaque-induced stenosis in a blood vessel. More particularly, the present invention relates to an expandable balloon catheter insertable into a blood vessel, which catheter comprises a plurality of strain gauges operable to report differential expansion of portions the balloon catheter under common pressure, thereby indicating the position and extent of regions of plaque within the vessel The device optionally includes radio-opaque markers to facilitate diagnostic interpretation of the strain-gauge output.
Most adults suffer to some degree from artherosclerotic plaque within blood vessels of the body. Plaque may limit blood flow through the vessel, causing dangerous tissue degeneration in extreme cases. Stenosis caused by plaque is often responsible for ischemic heart disease. The presence of plaque in blood vessels may also lead to thrombosis, endangering heart, lung, and brain tissue in particular.
Percutaneous transluminal angioplasty (PTA) is a treatment of choice for most stenotic conditions. In PTA, an inflatable balloon catheter or similar device is used to dilate a stenotic region of a blood vessel, thereby facilitating blood flow through the affected region. Various alternative and/or complementary procedures are used in treatment of stenotic conditions. These include arthrectomy, laser angioplasty, the use of stents, and the use of cryosurgical techniques to cool affected regions during or following compression of an affected area by angioplasty balloon.
The effectiveness of the above treatment methodologies is highly dependent on correct diagnostic localization of the areas to be treated. Yet, stenotic areas are, by their nature, not easily observable. A variety of strategies for locating regions of plaque within a blood vessel, and for characterizing that plaque, have been proposed and tested. Joye et al., in U.S. Pat. No. 6,602,246, teaches methods based on differential temperature readings from within a blood vessel, in recognition of the fact that the type of plaque particularly prone to create thromboses, termed “vulnerable plaque”, tends to be inflamed and therefore is at a higher temperature than standard stenotic plaque and normal healthy vascular tissue. Joye also lists angiography, intravascular ultrasound, angioscopy, magnetic resonance imaging, magnetic resonance diffusion imaging; spectroscopy, infrared spectroscopy, scintigraphy, optical coherence tomography, electron beam computed tomographic scanning, and thermography as prior art methods which have been used, with varying success, to locate regions of plaque within a vessel.
None of the above methods, however, has been found to be entirely successful, and most are complex and expensive. Thus there is a widely felt need for, and it would be advantageous to have, a device and method for locating and characterizing stenotic regions within a blood vessel, which device and method are relatively simple in construction and use, and relatively inexpensive.